The present invention relates to an optical system unit and a projector including the same optical system unit.
Currently, data projectors are used in many cases as image projectors for projecting images displayed on a screen of a personal computer, video images and, furthermore, images by image data stored in a memory card on to a screen.
The data projectors are such that a light source unit which includes a light source such as a metal halide lamp or an extra-high pressure mercury lamp or a light source made up of light emitting diodes is incorporated and light emitted from the light source unit is collected on to a display device which includes arrays of microscopic mirrors, called Digital Micromirror Devices (DMDs), or a display device made up of a liquid crystal plate, so that an optical image formed on the display device is projected as a full color image on to a screen via a lens group having a zooming function which constitutes a projection-side optical system.
In projectors like those described above, a light guiding or light smoothing unit such as a light tunnel or glass rod is disposed on an optical axis of light emitted from the light source unit so that the intensity of light is uniformly distributed across the width of a light beam which passes therethrough. However, the light beam shone on to the display device is distributed in a diffuse fashion due to the light beam passing through other light source-side optical systems after it has been emitted from the light smoothing unit, and this has sometimes increased unnecessary light.